Rubbing-machine.



G. H. EKSTROVI.

RUBBING MACHINE.

APPLICATION FILED DEc.22. 191s.

Patented Aug. 21,

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Y ks l GU-S'IAF H. EKSTROM, 0F BOCKFOBD, ILLINOIS, ASSIGNOB. TO BOCKFORD TOOL COMPANY,

OFA ROCKFORD, ILLINOIS, A CORPORATION 0F ILLINOIS.

Legami. l

Specification cfLetters Patent. I

' .nummer-MACHINE.

Patented Aug. 2i, ici 7.

Application led December 22, 1916. Serial No. 138,496.

To all whom t may concern.'

Be it known that I, GUs'rAF I-I. EKs'rRoM, a citizen of the United States, residing at Rockford, in the county lof Winnebago and State of Illinois, have'infvented certain new and useful Improvements in Rubbin'g-Machines, of which the following is a specification.

This invention relates to machines for rubbing or polishing plane surfaces and particularly to portablef machines of this class intendedfor use in rubbing and polishing the varnished surfaces of woodwork.

One of the objects of this invention is to produce' a 4machine of the class described which shall be of sufficiently small and compact construction to permit its use in 4rubbing and polishing the comparatively narrow depressed surfaces that occur inpaneled woodwork.

Another object of the invention is to simandv cheapen the construction while preserving a high degree of efficiency and durability. r

In' the accompanying drawings Figure 1 is a longitudinal central sectional view ofa portable rubbing machine embodying the features of my invention. Fig. 2 is a transverse vertical sectional view taken in the plane of line 2-2 of Fig. 1. Fig. 3 is a section on line 3-43 of Fig. 1. Fig. 4 is a detail view of one ofthe structural elements of the 'machine The embodiment selected for illustration comprises a body 1 consisting Aof a. tube or shell 2 having caps 3 and 4 screwed upon its ends.' The body 1 is adapted to be grasped in the hand of the operator.

Within the body -1 are two powercylinders and two pistons. In the embodiment herein shown, the istons are relatively stationary' and the cylinders reciprocate, the cylinders being rigidly secured together. The cylinders are indicated at 5 and 6'. The ad] acent ends vof the cylinders have heads 7 and 8. If desired, the cylinders 5 and 6 and the heads 7 and termediate tube 9 which serves to connect the twoI cylinders rigidly together.

The pistons for the cylinders 5 and 6 are indicated at 10 and 11, respectively. rlhese pistons may be secured to the body in any suitable manner. Herein they are shown as havingv flanged ends 12 which are clamped against the ends of the shell 2 by means of 8 may be integral with an in.

' thecaps 3 and 4. The pistons lOland 11 are herein shown as of sufficient length to serve las effective guides for the cylinders 5 and 6 as' the latter reciprocate. It will be noted that the pistons support the cylinders within the body.

The means for supplying pressure fluid,

as, for example, compressed air,l to the cylw inders comprises a rod or stem 13 which may, if desired, be formed integral with the piston `11, as herein shown. The stem 13 projects inwardly from the piston 11 and is axially alined with the piston. A duct 14 extends axially of the 13 and a nipple'15, said nipple being integral with the piston 11 and serving as a connection for a flexible air supply tube (not shown).

,In the ends of the tube 9 are secured bushings 16 which are of less'internal diameter than the tube 9, the inner ends ofy the bushings 16 thus forming annular shoulders 17 and 18. The openings through the bushings constitute ports through which pressure' fluid flows from the central chamber 9a of the tube 9,to the cylinders. The inner end por-v tion 19 of the stem 13 is of larger diameter than the remainder of the stem and is adapted to t snugly within the bushings 16. The length of the portion 19 is greater than the distance between the bushings 16. The duct 14 is arranged to communicate with the central chamber 9a of the tube 9 by means of piston 11, the stem,

two ports 20' and 21. These ports are in di'erent vertical planes as will be evident from Fig.` 1, or in other words, the ports are at diierent `points in the length of the portion 19. I

The end-22 of the portion '19 coperates with the annular shoulder 17 to shut off the ilow of pressure liiuid from the central chamber 9a to the cylinder 5. The opposite end 23 of the portion 19 serves as a valve cooperating with the annular valveshoulder `18 to shut 0H the flow of pressure iiuid from the chamber 9a tothe cylinder 6.

In the lower sides of the cylinders 5 and 6 cation of the4 cylinders, the pistons 10 and 11 alternately cover and uncover the exhaust ports 24. vThe air exhausted through the ports 24 escapes to the atmosphere through slots (hereinafter described) in the shell 2.

. are formed exhaust ports 24. In the recipro- In the present embodiment, the rubbing element is connected directly to the recipa rocatory structure 5, 6 and 9. Two brackets 25 embrace between them the tube 9 and are rigidlysecured together and to said reciprocatory structure. Said brackets project through two parallel slots 26 in the shell 2, as indicated in Figs. 2 and 3. These slots permit the escape of expanded air to the atmosphere.. The. brackets 25 incidentally prevent relative rotation between,the cyl-y inders and the pistons. To the lower ends 'of the brackets 25 is rigidly secured a wooden block 27 extending parallel with the body 1 and the `cylinders 5 and 6. The Iblock 27 may be faced with a strip of rubber 28, as shown. 29 is a strip of felt or other suitable friction material which is se- .cured over the facing28 by suitable means, as, for example, the nails 30.

.Assuming the parts to be in the position shown in Fig. 1, the operation is as follows:

Compressed air flows vfrom the duct 14 through the port 21 into the central chamber 9EL and thence into the cylinder 5. The cylinders 5 and 6 aref thereby caused to move toward the right. As soon as the shoulder 17 passes the end 22, the flow of air to the cylinder 5 is cut ofl", but the expansion of the air contained in said cylinder causes continuing right-hand movement of the cylinders.

A moment before theshoulder 18 passes thev shoulder 23, the exhaust ports 21 for the cylinder 5 are'uncovered, thus permitting exhaust of the air from the cylinder 5 to commence. As soon as the shoulder 18 has passed the shoulder 23 compressed air flows from the duct 14 through the port 2U into the central chamber 9a and 'thence intothe cylinder 6. Therefore, as soon as themomentum of the movingy parts can be overcome, the cylinder 6 'begins to move toward the left. The supply of compressed air to the cylinder 6 is cut off as'soon as the shoul-` der 18 passes the shoulder 23.in the left-hand movement of the cylinders. The cylinders are thus-rapidly reciprocated, carrying with them the rubbing element. The pressure of y the air trapped inthe cylinders after :the exhaust ports 24 are covered bythe pistons preventsthe heads 7 and8 from Striking the pistons.- A In operation, the workman grasps the .bodyl and slides the machine over the surface to be rubbedor polished, suitable abra'- sive or polishing `material having been placed upon said surface. While themachine is being thus moved, the cylinders 5 and 6 and the attached pad29- are rapidly reciprocated to' rub or polish the surface against which the workman is pressing the 0 machine.

As will be apparent; the machine herein illustrated and described is of very 'simple construction and comprises a minimum number of moving parts.

The invention herein shown is not limited equilibrium.

I claim as my invention:

1. A portable rubbing or polishing machine having, in combination, a tubular body, istons secured tothe body within the ents of the body, said pistons being axially alined, two cylinders slidablyl supported by said pistons, the adjacent ends of said cylinders having heads, a tube rigidly connecting said heads, said tube-having internal annular shoulders near ,its ends, a stem rigidly connected to one of the pistons and extending axially thereof, the inner end portion of said stem having two annular shoulders adapted to coact with the shoulders in the tube, the distance between 'the shoulders on the stem being greater than the distance .between the shoulders in the tube,'said stem and the piston to which it is attached having a pressure-fluid supply duct, which duct communicateswith the periphery of the inner I:end`portion of the stem, each of the cylinders having an exhaust port arranged to be covered and uncovered by the adjacent piston in the reciprocation of lthecylinders, and rubbing means actuated by the cylinders.

chine having, .in combination, a body, pistons secured to the body, two cylinders containing said pistons, the adjacent en'ds of said cylinders having heads, a'tube rigidly connecting said heads, said tube having internal annular shoulders near its ends, a stem rigidly connectedto one of the pistons, the inner end portion .of said stem having two annular shoulders adapted to coact with the shoulders in the tube, the distance between the shoulders on the stem being greater than the distancfJ between the shoulders in the tube, said stem and the piston to which it is attached having a pressure-fluid supply duct, which duct communicates with the peripheryY` of the inner end portion of the stem, each of the cylinders having an exhaust port arranged to be covered-'and uncovered by the adjacent piston in the reciprocation of the cylinders, and rubbing means actuated by the cylinders. v

3. A portable rubbingor polishing machine having, in combination, a body adapted to be graspedi in the hand of the operl ator, pistons secured to the body within-the ends of the body, said pistons being axially alined, two cylinders shdably supported by '5 said pistons, the adjacent ends of said cylinders having heads, a tube rigidly connecting said heads, said tube having. internal annular shoulders near its ends, a stem rigidly connected to one of the pistons and l extending axially thereof, the iniierj endportion of said stem having two annular shulders adapted tocoact with the shoulders in the tube, said stem and the piston to which it is attached having a pressure-- fluid supply duct, which duct communicates vv 4. A portable rubbing or polishing machine having, in combination, a body, pistons secured t0 the body within the ends ofthe body, two cylinders containing said pistons, the adjacent Lends of said cylinders having heads, a tube rigidly connecting said heads, said tube having internal -annular shoulders nearits ends, a stem rigidly connected to one of the pistons, the inner end portion of said stem having two annular 3o' shoulders adapted to coact with the shoul- .k ders in the tube, said] stem and the piston to which it is attached having a pressureiuid supply duct, which duct communicates with the periphery of the inner end portion of the stem, exhaust means for the cylinders, and rubbing means actuated by the cylinders.

5. A portable rubbing or polishing machine having, in combination, a body, pis- 4o tons secured to the body, two cylinders containing said pistons, said cylinders having a central chamber moving with the cylinders, said chamber having internal annular shoulders near its ends, a stem rigidly connected to one lof the pistons, the inner end portion of said stem having. two annular shoulders adapted to coact with the shoulders -in the chamber, the distance between the shoulders on the stem being greater than v the distance between the shoulders in the chamber, said stem and the piston to which it is attached having a pressure-Huid supply duct, Awhich duct communicates with the periphery ofthe inner end ortion of the stem, each 'of the cylinders av'ing yan exhaust port arranged to` be covered and Juncovered by' the adjacent piston in ythe reciprocation ofA the cylinders, and rubbing v means actuatedby the cylinders.

6. A portable rubbingpr polishing machine having, in combination, relatively s tationary pistons, two cylinders containing said'pistons, said cylinders havingl a central chamber moving vwith the Cylinders, said i chamber having internal annular shoulders actuated by the cylinders. 7. A portable rubbing or polishing machine having, in combination, a pair of cyl- 30 inders rigidly connected'togethena pair of pistons for the cylinders, lsaid pistons being rigidlyconnected together, a rubbing element rigidly connected to one of said pairs of elements, said cylinders having a. lcena5 tral'chamber, said chamber having internal annular shoulders near its ends, a stem rigidly connected to on'e of the pistons, the ,inner end Iportion of said stem/ having two annular shoulders Aadapted to coact with 9o the shoulders inthe chamber, the'V distance between the shoulders on the stem being greater than the distance between the shoulders in the chamber, said stem having a pressure-Huid supply `duct arranged for communication with a source of pressurefluid supply and' also communicating with the periphery of the inner endportion of ghe stem, and exhaustnieans for the cylin-l ers. l 8. A portable rubbing or polishing machine having, in combination, relatively stationary pistons, two cylinders containlng said pistons, said cylinders having a central chamber moving with the cylinders, l

said chamber having internal annular shoulders near its ends, Aa'relatively stationary stem having two annular shoulders adapted to coact with the shoulders inthe chamber,

1 the distance 'between the shoulders on the 110 stem being greater than the distance be- 'tween the shoulders in the chamber, said stem having a duct arrangedfor communication with .a source of pressure-Huid, which duct communicates with the periphery of the stem between the shoulders on the stem, exhaust'means for the cylinders, nd rubbing means actuated by the cyliners. A

9. A' portable rubbing or polishing ma- 120 chine having, in combination, a pair of cylinders rigidly connected together, a pair of pistons lfor the cylinders, said" pistons being .rigidly connected together2 rubbing means actuated by one of said palrs of ele-* f ments, said cylinders having a central chamber, said chamber having internal annular shoulders near its ends,'a stem rigidly connected to one of said pairs of elements, said stein having two annular shoulders adapted to coact'with the shoulders in the chamber, said stem having a pressure-iuid supply lduct arrangedfor communication with a source of pressure-fluid -supply and also. 'communicating with the periphery of the stem betweenthe shoulders on the stem, and exhaust means for the cylinders.

10. A portable rubbingfor polishing machine having, in combination, relatively stationary pistons, two cylinders containing said pistons, said cylinders having a central chamber moving with the cylinders, said chamber having valve means, coperating valve means attached to one of the pistons, means for supplying pressure-Huid to said chamber, exhaust means for the cylinders, and rubbing means actuated by the cylinders.

11. A' portable lrubbing or polishing mal chine having, 1n combinatioma pair ofcylinders rigidly connected together, a pair of pistons for the cylinders, said pistons being rigidly connected together, rubbing means actuated by one of said pairs of elements,'there being a chamber between said cylinders, said chamber having internal annular shoulders near its ends, a stem connectedto one of said pairs of elements and having two annular shoulders adapted to coact with the shoulders in the chamber,

4said stem having a pressure-fluid supply' duct arranged for communication with a source of pressure-fluid supply and also communicating with thel periphery of the 'ber having annular valve means, coperat- 1ng annular valve means connected to one of said pairs of elements, means for supplying pressure-Huid tothe chamber, and e"x haust-means for the cylinders.

13. A. portable rubbing `or polishing machine having, in combination, a body, two single-acting cylinders rigidly secured together at their adjacent. ends and slidably supported bythe body,I the closed ends of said cylinders being adjacent each other, pistons within said cylinders and secured to the opposite ends of the body, means for controlling the How of pressure-Huid to and from the cylinders, a rubbing element, and means-rigidly connecting the rubbing elementl to the cylinders, said connecting means extending through an opening in the body and serving to prevent yrelative rotation between the body and the cylinders.

In testimony whereof, I have hereunto set my hand.

l l GUSTAF EKSTROM. 

